The invention relates to a universal mobile telecommunications system having an expanded cordless telecomunnication system.
Modern mobile communications, for example mobile telecommunications for the transmission of voice, data, text, graphics, fixed and moving images, is divided up into a private sector and public sector in analogy with stationary communications (for example ISDN communications system; Integrated Services Digital Network). In addition, in the case of mobile telecommunications (first and second generation), a distinction is made between cellular telecommunications and cordless telecommunications. Cordless telecommunications has until now been based substantially on cordless telecommunications systems for home and office applications, while cellular telecommunications is dominated by the use of mobile radio telecommunications systems.
For the mobile telecommunications systems mentioned above, in particular those of the second generation, in most cases a TDMA method (Time Division Multiple Access) is used for the accessing and multiplexing of the signals to be transmitted. For future mobile telecommunications systems (for example third generation), however, the CDMA transmission method (Code Division Multiple Access) will also gain in significance, not least because of the likely use of cell-oriented transmission methods (ATM method; Asynchronous Transfer Mode). The reason for this is that, for an ever increasing number of communications and information services on offer and at the same time increasing requirements demanded in terms of the quality and quantity of the bit rates for transmission, an ever greater role will be played not only by the accessing and multiplexing methods but also by the optimized signal coding, channel coding for a flexible air interface.
The TDMA and CDMA transmission methods ultimately form the basis for the various system standards in mobile telecommunications. With regard to the TDMA method, the cordless telecommunications systems currently introduced on the market are set up in accordance with, inter alia, the digital pan-European DECT standard (Digital European Cordless Telecommunication) and the digital CT2 standard (Cordless Telephone 2), while the mobile radio telecommunications systems are set up in accordance with the worldwide GSM standard (Groupe Spxc3xa9ciale Mobile; Global System for Mobile Communications).
The further development of mobile communications in a spiral of effects according to FIG. 1 (Telcom Report 15; 1992; issue 2, pages 57 to 59) will lead to the already mentioned third generation of mobile telecommunications systems, in which the existing separation between cellular and cordless telecommunications is brought to an end. This third generation of mobile telecommunications is distinguished by universal mobility (in terms of time and location), in which each communications subscriber can be reached anywhere and at any time. With respect to this universal mobility, a distinction is drawn between equipment-related mobility via air connections and person-related mobility via air connections and cable connections. The inclusion of both aspects in universal mobile communications leads to xe2x80x9cAdvanced Mobilityxe2x80x9d with a universal mobile telecommunications system (UMTS=Universal Mobile Telecommunication System) in conjunction with universal personal telecommunications (UPT=Universal Personal Telecommunication). The universal mobile telecommunications system (UMTS) requires both flexible air interfaces and an intelligent network infrastructure. It is ensured by such a system structure that, on the one hand, mobile subscribers can communicate with one another at different speeds and traffic densities and, on the other hand, a large number of telecommunications and message services (information services) can be offered with high quality and capacity.
In FIG. 2 there is represented on the basis of the publication Telcom Report 15; 1992; issue 2, pages 60 to 63 a xe2x80x9cUniversal Mobile Communicationsxe2x80x94Advanced Mobilityxe2x80x9d scenario with the various applications with respect to the cell radius. According to this, the set-up of the universal mobile telecommunications system (UMTS) is subdivided into different communications cells for the application areas (office, home, town and country). These cells may be linked to one another two-dimensionally (country, town) or three-dimensionally (buildings). According to the representation in FIG. 2, the various types of mobile telecommunications (cordless, radio and satellite telecommunications SL-TK, MF-TK, SF-TK) are represented separately or in a mixed form in dependence on the cell radius.
In its pure, separate form for office and home applications, cordless telecommunications SL-TK takes place in the picocell range. In this picocell rangexe2x80x94with a picocell radius PIZR of up to 200 m (transmission range)xe2x80x94there is at least one picocell PIZ with a cordless telecommunications system SL-TKS. The cordless telecommunications system SL-TKS in this case comprises a picocell-individual base station PIZ-BS (cordless base station) and at least one picocell-individual mobile station PIZ-MS (cordless mobile station) assigned to the base station PIZ-BS. Ifxe2x80x94as above and in the followingxe2x80x94terms with the ending xe2x80x9ccell-individual(ly)xe2x80x9d are used in conjunction with an object/an activity/a characteristic, the object/the activity/the characteristic which is dedicated to a cell (for example a picocell, microcell, macrocell and hypercell) or belongs to a cell is meant by this.
In its pure, separate form for town or country applications, mobile radio telecommunications MF-TK takes place in stationary property (for example buildings) and/or in dynamic, mobile property (for example a car, train, etc.) in the macrocell range. In this macrocell rangexe2x80x94with a macrocell radius MAZR of, for example, up to 20 km (transmission range)xe2x80x94, which covers the picocell range with the picocell PIZ and a microcell range with at least one microcell MIZ, there is at least one macrocell MAZ with a mobile radio telecommunications system MF-TKS. This mobile radio telecommunications system MF-TKS in this case comprises a macrocell-individual base station MAZ-BS (mobile radio base station), which may be of a stationary or mobile set-up (for example a car, train), and at least one macrocell-individual mobile station MAZ-MS (mobile radio mobile station) assigned to the base station MAZ-BS.
As an addition to cordless and mobile radio telecommunications SL-TK, MF-TK, satellite telecommunications SF-TK takes place in a hypercell range. In this hypercell rangexe2x80x94with a hypercell radius HYZR of several hundred kilometers (transmission range)xe2x80x94there is at least one hypercell HYZ with a satellite telecommunications system SF-TKS. This satellite telecommunications system SF-TKS in this case comprises a satellite SAT, for example positioned in geostationary earth orbit, of a hypercell-individual base station HYZ-BS, which may be of a stationary set-up as an earth station ES or a mobile set-up as a mobile earth station MES (for example in an airplane, ship, truck, etc.), and at least one hypercell-individual mobile station HY-ZMS assigned to the base station HYZ-BS.
In the case of the mixed form of the three types of mobile telecommunications mentioned above, there is used, for example, for the realization of the xe2x80x9cadvanced mobilityxe2x80x9d concept within the universal mobile telecommunications system (UMTS) a network infrastructure NIS (ISDN=Integrated Services Digital Network, B-ISDN=Broadband Integrated Services Digital Network).
This network infrastructure NIS is, for example, a narrowband or broadband ISDN communications system. In the publication Telcom Report 8; 1985; special issue with the title xe2x80x9cDiensteintegrierendes Digitalnetz ISDNxe2x80x9d [Integrated Services Digital Network ISDN]xe2x80x94entire documentxe2x80x94there is described a narrowband ISDN communications system and in the publications Telcom Report 14; 1991; special issue with the title xe2x80x9cTelcom ""91xe2x80x9dxe2x80x94pages 12 to 19 (xe2x80x9cVision ONExe2x80x94Optimierte Netz-Evolutionxe2x80x9d [Vision ONExe2x80x94Optimized network evolution])xe2x80x94and Telcom Report 14; 1991;xe2x80x94pages 36 to 39 (xe2x80x9cGrundsteine fxc3xcr schnelleren B-ISDN-Aufbauxe2x80x9d [Foundation stones for faster D-ISDN set-up]), pages 40 to 43 (xe2x80x9cBreitband-ISDN ante portasxe2x80x9d [Broadband ISDN ante portas]), pages 258 to 261 (xe2x80x9cSchrittmacher fxc3xcr bitratenvariable Breitband-kommunikationxe2x80x9d [Pacesetter for bit-rate-variable broadband communications])xe2x80x94there is described a broadband ISDN communications system.
This network infrastructure NIS is bidirectionally connected to the picocell-individual base stations PIZ-BS of the cordless telecommunications system SL-TKS, the macrocell-individual base stations MAZ-BS of the mobile radio telecommunications system MF-TKS and/or via the stationary earth station ES to the satellite SAT of the satellite telecommunications system SF-TKS.
However, to be able to install such a universal mobile telecommunications system UMTS, represented in FIG. 2 and described above, a series of problems still have to be solved.
This series of problems relates to
concepts for introduction (for example necessary technical compatibility or interaction with existing systems and networks with regard to area coverage, extent of use, possible communication and information services etc.);
a long-term concept with harmonized integration or complex xe2x80x9cinterworkingxe2x80x9d in a multi-system or multi-operator scenario;
possible substitutions (for example between line connections and air connections or between UPT and UMTS);
use of synergetic effects in development and production;
a possible delaying and influencing of the universal mobile telecommunications system (UMTS) by constant improvements in the systems of the second generation (advanced GSM, advanced DECT);
technical, legal, political, social uncertainties (for example interworking of distributed databases, future frequency assignment, possible health impairment caused by radio).
Given this large number of problems, an evolutionary further development of the universal mobile telecommunications system (UMTS) appears to be probable. In the course of this evolutionary further development, cellular interactive telecommunications (mobile radio) and cordless interactive telecommunications (cordless technology) are being advanced step by step up to universal mobile telecommunications (UMTS) with xe2x80x9cadvanced mobilityxe2x80x9d.
If mention is made in the following of a universal mobile telecommunications system according to the representation in FIG. 2, this means, inter alia, a telecommunications system which
is based on different accessing, multiplexing, coding and modulation methods (TDMA and CDMA methods),
is based on the use of the cell-oriented transmission method (ATM=Asynchronous Transfer Mode) in the network infrastructure NIS,
can be used for different telecommunications standards (DECT, GSM, advanced DECT, advanced GSM) and
can be used for different communication and message/information services (for example voice dialog, information transmission in the form of data, text and image and also emergency call, locating and navigation services).
European references EP 0 418 096 A2 discloses a cellular mobile radio system (macrocell) which is subdivided into a plurality of subcells (picocells). Each of these subcells is assigned a duplex repeater station, by means of which a macrocell-individual radio connection can be set up between a macrocell-individual base station and a low-power mobile unit respectively assigned to the subcells. The duplex repeater station has in this case the task of receiving converting and amplifying radio signals transmitted from the low-power mobile units to the macrocell-individual base station and of receiving, converting and Attenuating radio signals transmitted from the macrocell-individual base station to the low-power mobile units (tasks of a transponder).
U.S. Pat. No. 4,748,655, which comes closest to the subject-matter of the application, discloses portable telephones which can be connected via a multiplicity of different network coupling devices (gateways), such as for example shared radio units, radio telephones, cordless telephones or private branch exchanges, to a cellular radio network. In addition, the portable telephone can also be used within the cellular radio network as a pager. The user of such a multifunctional telephone can consequently take part in network telecommunications without owning a radio telephone required for telecommunication in the cellular radio network. This participation is ensured in this case by the various gateways. Of the various gateways, the shared radio unit, designed as a multichannel arrangement, is particularly able to serve a multiplicity of the said multifunctional telephones within a limited area, smaller than the cells of the radio network. The shared radio unit, which is preferably transportably designed and used for example in public areas such as railroad stations, airports, trains or buses, serves for the said telecommunication purposes exclusively as a connection and conversion unit between a base station assigned to the cellular radio network and the multifunctional telephones. The operating principle of the shared radio unit consequently corresponds to a transponder, such as that known, for example, from satellite technology.
U.S. Pat. No. 4,759,051 discloses a cellular radio telephone system in which a geographical radio area with a cellular cell station is subdivided into a plurality of radio cells. Each of these radio cells contains a transponder, the transponder picking up, amplifying and emitting again the radio signals to be transmitted which are on the radio link between the portable radio units and the cell station.
In the IEEE Communications Magazine 30, December 1992, No. 12, pages 54 to 62, the conception and preconditions of a universal mobile telecommunications system (UMTS) for the third system generation of mobile telecommunications are discussed.
The object underlying the invention is to specify a universal mobile telecommunications system in which, in the course of further development of mobile telecommunications according to the spiral of effects shown in FIG. 1, a picocell-individual cordless telecommunications system can be expanded (universally) to communications cells with different cell radii.
In general terms the present invention is a universal mobile telecommunications system having an expanded cordless telecommunications system, which covers a picocell range with at least one picocell and a cell range of higher order than the picocell range, with at least one cell of a higher order than the picocell. The system has a picocell mobile station which is assigned to the picocell and be connected by telecommunications to a relay station contained in the picocell. The relay station is adapted such that it can be connected by telecommunications to a transmitting/receiving arrangement contained in the higher-order cell. The relay station is allocated not only the function of telecommunications connection to the transmitting/receiving arrangement assigned to the higher-order cell (for forming a cordless telecommunications system including the picocell mobile station and covering the picocell), but also the function of a picocell base station.
The major advantage of the universal mobile telecommunications system according to the invention is that a cordless telecommunications system expanded to communication cells with differing cell radii manages in the expanded cordless range with a lower transmitted power for cordless mobile stations and, as a result, the loading brought about by a user of the cordless mobile station by electromagnetic waves in cordless transmission is reduced. A further major advantage of the universal mobile telecommunications system according to the invention is that the possibility of higher-quality telephony, up to videotelephony, is provided by the expanded cordless telecommunications system, in particular in the picocell and microcell range. The reason for this is that, the smaller the cell radius of a communications cell, the greater generally the capacity available per unit area and consequently the usable bit rate for the respective application. The universal mobile telecommunications system according to the invention consequently already offers in the course of the spiral of effects for universal mobile telecommunications with advanced mobility a simple possibility for connecting cellular and cordless mobile telecommunications systems to each other. By this connection between the two mobile telecommunications systems and the development in parallel with this of a broadband ISDN communications system, there can consequently be set up a universal mobile telecommunications system in which a telecommunications subscriber can reach his communications partner anywhere (advanced mobility).
Advantageous developments of the present invention are as follows.
The relay station has at least one first transmitting/receiving antenna for the telecommunications connection to the transmitting/receiving arrangement assigned to the higher-order cell and at least one second transmitting/receiving antenna for the telecommunications connection to the picocell mobile station. In a further embodiment the first transmitting/receiving antenna is designed as a directional antenna.
Two second transmitting/receiving antennas are provided and are designed as diversity antennas.
A first transmitting/receiving arrangement is designed as a cordless base station assigned to a microcell.
A second transmitting/receiving arrangement is designed as a mobile radio base station assigned to a macrocell.
When the first transmitting/receiving arrangement is a cordless base station, the first transmitting/receiving arrangement is connected to a first switching system.
When the second transmitting/receiving arrangement is a mobile radio base station, the second transmitting/receiving arrangement is connected to a first switching system.
A third transmitting/receiving arrangement is designed as a second switching system with an air/line interface. In a further embodiment the first and/or second switching system is designed as a private branch exchange.
A fourth transmitting/receiving arrangement is designed as a satellite radio telecommunications system with a satellite, arranged in geostationary earth orbit, and an earth station.
The cordless telecommunications system and a first expanded cordless telecommunications system are set up as a DECT system.
The cordless telecommunications system is set up as a DECT system and a Second expanded cordless telecommunications system is set up as a cordless/mobile radio system.
The cordless telecommunications system and the expanded cordless telecommunications system are set up as a vidoetelephony system.